Previously, an electronic control device, which includes a case and a cover for receiving a circuit board, is known. For example, in JP2014-187728A, a seal groove is formed in a distal end of a peripheral wall of a case, and a seal material is filled in the seal groove. A projecting portion of a cover is inserted into the seal groove to seal between the cover and the case.
In JP2014-187728A, in a case where two wall portions, which are located on two opposite sides, respectively, of the seal groove, have an identical height, when the projecting portion of the cover is inserted into the seal groove in a state where the seal material is filled in the seal groove, the seal material may possibly intrude into an inside of the case.